[Converted from Gnats 2560]
In file remote.c, the function remote_send is used to send a packet to the remote target and receive a response packet back to it. It checks whether the response packet is an 'ENN' error response with the test
if ((*buf)[0] == 'E')
error (_("Remote failure reply: %s"), *buf);
This test is too weak: if the response packet contains valid data which happens to begin with an 'E' then it will be incorrectly treated as an error.
The correct test is performed in the function packet_check_result in this file:
if (buf[0] == 'E'
&& isxdigit (buf[1]) && isxdigit (buf[2])
&& buf[3] == '\0')
/* "Enn" - definitly an error. */
return PACKET_ERROR;
In fact, this function should be used throughout this file to check all response packets; e.g. in the function remote_rcmd there is the code
if (buf[0] == '\0')
error (_("Target does not support this command."));
if (buf[0] == 'O' && buf[1] != 'K')
{
remote_console_output (buf + 1); /* 'O' message from stub. */
continue;
}
if (strcmp (buf, "OK") == 0)
break;
if (strlen (buf) == 3 && buf[0] == 'E'
&& isdigit (buf[1]) && isdigit (buf[2]))
{
error (_("Protocol error with Rcmd"));
}
where the tests essentially duplicate the code in packet_check_result (though strlen is a very inefficient means of checking that the 4th character in a buffer is a NUL!).
Release:
insight 6.8

From: Daniel Jacobowitz <drow@false.org>
To: richard.stuckey@arc.com
Cc: gdb-gnats@sources.redhat.com
Subject: Re: remote/2560: valid reponse packet can be treated as 'ENN'
error packet
Date: Tue, 2 Dec 2008 12:19:13 -0500
On Tue, Dec 02, 2008 at 05:04:33PM -0000, richard.stuckey@arc.com wrote:
> This test is too weak: if the response packet contains valid data which happens to begin with an 'E' then it will be incorrectly treated as an error.
remote_send is only used in four cases: p/P and g/G. If you
encountered it in one of those, I suggest sending back lowercase
hex rather than uppercase hex.
That does not invalidate your correct report; merely a suggestion.
--
Daniel Jacobowitz
CodeSourcery

From: "Richard Stuckey" <Richard.Stuckey@arc.com>
To: "Daniel Jacobowitz" <drow@false.org>
Cc: <gdb-gnats@sources.redhat.com>
Subject: RE: remote/2560: valid reponse packet can be treated as 'ENN'error packet
Date: Tue, 2 Dec 2008 17:22:38 -0000
Yes, it was getting a register frame: the first hex digit for the first
register was 'E' !
Good idea about the lowercase.
Thanks
-----Original Message-----
From: Daniel Jacobowitz [mailto:drow@false.org]=20
Sent: 02 December 2008 17:19
To: Richard Stuckey
Cc: gdb-gnats@sources.redhat.com
Subject: Re: remote/2560: valid reponse packet can be treated as
'ENN'error packet
On Tue, Dec 02, 2008 at 05:04:33PM -0000, richard.stuckey@arc.com wrote:
> This test is too weak: if the response packet contains valid data
which happens to begin with an 'E' then it will be incorrectly treated
as an error.
remote_send is only used in four cases: p/P and g/G. If you
encountered it in one of those, I suggest sending back lowercase
hex rather than uppercase hex.
That does not invalidate your correct report; merely a suggestion.
--=20
Daniel Jacobowitz
CodeSourcery